Grade 12 - Momentum (Linear Mechanical Systems)

PRESCRIBED LEARNING OUTCOMES

• describe linear momentum and factors affecting it
• describe impulse and factors affecting it
• describe the relationship between impulse and momentum
• explain the law of conservation of linear momentum
• describe how the concept of conservation of momentum applies to common situations
• identify systems in which the momentum of a fluid is used
• use the concept of conservation of linear momentum to analyse collisions in two dimensions and determine if kinetic energy is conserved

SUGGESTED INSTRUCTIONAL STRATEGIES

• Ask students to waterproof a weigh scale, mount it vertically, and direct a horizontal stream of water at it. Students then compare the force reading with the calculation of the force from the rate of change of momentum of the water.
• Have students investigate the use of momentum of fluids in such applications as power car washes, water-jet cutting, and log debarking. Each student selects one application and reports to the class on the pressure used and how momentum is regulated.
• Ask students to investigate conservation of linear momentum by dropping a weight onto a moving toy boxcar and comparing momentum before and after the drop. Alternatively, students could slowly fill the boxcar with sand as it moves, observing the resulting change in speed.
• Have students in groups develop explanations of why karate experts bounce their hands or heads on boards or bricks when attempting to break them.
• As a class, discuss the "water hammer" effect in water pipes and its potential to cause damage in houses.
• Provide students with simulation software to model and analyse collisions.

SUGGESTED ASSESSMENT STRATEGIES

• Ask students to explain the concepts of impulse and momentum as related to collisions. Check their understanding by asking them to:
  • compare impulse and momentum
  • create graphs of force-time relationships
  • explain the effect of the law of conservation of momentum
  Note the extent to which students:
  • make reasoned predictions based on their understanding of linear momentum
  • accurately graph relationships
• Have students describe the differences between metal and wooden baseball bats as examples of momentum in a linear system. Look for evidence that they:
  • distinguish between impulse and momentum
  • apply the law of conservation of momentum
  • accurately calculate values
• Ask students to research bicycle helmets as examples of a momentum and impulse system. Then have them develop their own designs. When assessing their designs, look for:
  • identification of the relevant forces and calculations
  • recognition of the effects of momentum and impulse on biological systems
  • abilities to explain the design principles of the system
  • application of the law of conservation of momentum
  • identification of impulse and the factors affecting it

RECOMMENDED LEARNING RESOURCES

Applications of Physics 11 and 12 develops an understanding of the concepts of physics through the design, construction, and use of a variety of devices. Although the resources listed below provide a range of teaching and learning opportunities in physics, none of them provide a comprehensive resources package that completely supports the philosophy and approach of the British Columbia curriculum in the applications of physics. Please see the Appendix B Introduction for further information.

Print Materials

• Advanced Level Physics, Seventh Edition
• Cambridge Coordinated Science: Physics
• Conceptual Physics, Third Edition
• Heinemann Advanced Science: Physics
• Physics: Principles and Problems, American Edition
• Physics: Principles and Problems, Canadian Edition

• Hidden by Time: Seeing the Physical World with High-Speed Cameras
• Physics Demonstrations in Mechanics: Parts III - VI

• Interactive Physics: Student Edition

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Last Modified: April 1, 1998.
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